Current endoscopic technology allows trained medical personnel to insert an ultrasonic transducer probe into the body for the purpose of obtaining internal images of the body through the use of ultrasound technology. These ultrasound images assist technicians in diagnosing various internal conditions without the need to perform invasive exploratory surgery.
Conventional ultrasonic transducer probes are comprised of a transducer array enclosed within an acoustic fluid chamber. Acoustic fluid contained within the chamber is provided to assist in the propagation of ultrasound pulses in the area between the transducer array and transducer array lens. Further, the transducer tip utilizes a combination of mechanical seals and gaskets in order to retain the acoustic fluid within the chamber.
Typically, a transmission assembly is provided within the probe for manipulating or moving the transducer array or transducer tip about the probe. The transducer tip is typically coupled to an elongated flexible probe tube which allows the transducer tip to be inserted into the body from a remote position outside of the body. The elongated flexible probe tube is itself attached to a control handle having a steering device to control the movement and direction of the elongated flexible probe tube.
In operation, the transducer array, which is contained within the chamber, generates a series of ultrasound pulses which are transmitted from the transducer array, through the acoustic fluid contained in the chamber, and out through the transducer array lens towards a target area. Accordingly, the pulses are reflected back from the target through the transducer array lens into the chamber and through the acoustic fluid to the transducer array.
In order to operate in accordance with the designed intent, however, the acoustic fluid contained within the chamber must be kept free from foreign matter, such as gas. Nevertheless, such foreign matter may enter the chamber through mechanical seals and gaskets, used to retain the fluid within the chamber, resulting in a contamination of the acoustic fluid. The foreign matter is able to enter the fluid chamber through the mechanical seals and gaskets primarily as a result of pressure and temperature variations which act directly or indirectly upon the acoustic fluid contained within the chamber. If the acoustic fluid actually becomes contaminated, the foreign matter interferes with the propagation of the ultrasound pulses through the acoustic fluid causing the ultrasound pulses to be randomly reflected and dispersed about the chamber. Such foreign matter interference leads to a marked degradation in the quality of the images which are generated from the ultrasound pulses.
For example, during normal operation and transportation, the acoustic fluid contained within the chamber is subject to fluctuations and variations in both temperature and pressure. As a result of the variations in temperature, the fluid within the chamber expands and contracts thereby creating a chance of foreign matter introduction into the fluid and the chamber.
For instance, in normal operation wherein the probe is inserted into the body, the temperature of the acoustic fluid within the chamber typically rises. The rise in temperature is mainly attributed to such heat sources as internal body heat and the heat generated by the transducer array as ultrasound pulses are generated. As the temperature of the acoustic fluid in the chamber starts to rise, the acoustic fluid starts to expand and assert pressure against the internal surfaces of the chamber. As pressure is asserted against the internal surfaces of the chamber, the internal pressure of the chamber rises forcing the acoustic fluid out of the chamber through the associated mechanical seals and gaskets. Correspondingly, when the acoustic fluid in the chamber cools from such a heated state, the acoustic fluid necessarily contracts creating a vacuum within the chamber. The vacuum within the chamber draws air or gas, or possibly body liquids, into the chamber through the mechanical seals and gaskets, thereby introducing foreign matter into the acoustic fluid of the chamber.
Similarly, when the probe is inserted into a body, the pressure within the chamber typically rises from pressure being asserted against the array lens. Such pressure is typically caused by the internals of the body exerting pressure against the array lens. As the pressure acting on the array lens rises, the acoustic fluid contained within the chamber correspondingly asserts a proportional pressure against the internal surfaces of the chamber. As pressure is asserted against the internal surfaces of the chamber, the internal pressure of the chamber rises forcing the acoustic fluid out of the chamber through the mechanical seals and gaskets. Accordingly, when the pressure acting on the array lens subsides, the internal pressure of the chamber subsides creating a vacuum within the chamber. The vacuum within the chamber draws air or gas, or possibly body liquids, into the chamber through the mechanical seals and gaskets, thereby introducing foreign matter into the acoustic fluid and chamber.
Likewise, similar temperature and pressure variations can occur when the transducer probe stored or is transported, thereby creating an opportunity for the introduction of foreign matter into the chamber of the probe. For example, in air transport there are temperature and pressure variations which create similar conditions as those illustrated above, wherein foreign matter may be introduced into the acoustic fluid of the chamber.
Currently available transducer probes address contamination problems by various solutions directed towards the removal of foreign matter from an acoustic liquid, the foreign matter typically being air bubbles. Such solutions range from the usage of acoustic fluid reservoirs to chamber venting valves in order to remedy the foreign matter contamination. However, current technology is not directed towards preventing the contamination problem. Accordingly, the presently available solutions do not address the problem of preventing the contamination, but rather only remedy the contamination after it has already occurred. Further, current technology in the area does not address the common problems of pressure and temperature variations which take place within acoustic fluid chambers, leading to foreign matter introduction.
It is therefore desirable to provide an apparatus which can prevent the invasion of foreign matter into an acoustic fluid chamber as a result of such pressure and temperature variation that take place within acoustic fluid chambers.